2009 Paper 2 (Section: 8 )
11. A test paper consists of 40 questions. Each question is followed
by four choices of answer, wherc only one of these is correct.
(a) Salma answers all the questions by randomly choosing an
answer for each question.
and
(i) Estimate the number of questions she answered correctly. 10

In this scenario, since there are four answer choices for each question and only one is correct, the probability that Salma randomly selects the correct answer for any single question is 1 out of 4, or 25%. Therefore, if she answers all 40 questions, we can estimate the number of questions she gets right by multiplying the total questions by the probability of a correct answer: . So, on average, we expect that Salma would answer about 10 questions correctly if she guesses on all of them.

Now, it’s worth noting that this is an estimation based on probability and random guessing. The actual number she may get correct could vary, especially due to the nature of randomness. Sometimes she might be lucky and guessed more correctly or, conversely, might compute even fewer right answers purely by chance! It’s all part of the guessing game!